It is well-known that X-ray photographing equipment should be operated in such manner, that during the time period of exposure an unexposed film is fixed in a plane corresponding to the area from which the picture is to be taken, and the equipment should provide for a fresh film supply.
A common feature of much earlier equipment is that the exposure and the changing of the films occur in each case at the corresponding X-ray workplace. In other X-ray equipment a so-called magazine store, adapted to store a plurality of unexposed and exposed films, is built together with a developing apparatus.
The film producing technique carried out at individual workplaces increases the demand on space and material.
In the photographing systems equipped with a picture amplifier (image intensifier), the role of the picture amplifier lies in the correct determination of the area of exposure and in obtaining preliminary picture information. The actual exposure, in the earlier systems, is not taken through the picture amplifier, but it is taken by the exposure of an unexposed film arranged across the path of the X-ray beams. It is well-known in the art that substantially higher radiation intensity is required for taking an exposure that to the monitoring of a picture through the picture amplifier. In such photographing systems the X-ray specialist does not have the possibility of checking the picture through a monitor during the exposure and, for that reason, frequently more exposures are taken than it is required.
According to another conventional photographing method the image obtained on the screen of the picture amplifier is transferred through a suitable optical light splitting device first to a television recording camera and second to a special photographing unit (spot-exposure technique). The light intensity of the picture on the screen of the picture amplifier is generally not sufficient to enable the preparation of pictures of acceptable quality with practical film sensity values. Therefore when exposures are taken the radiation intensity is increased in a pulse-like manner and the light splitter is adjusted in such a way that the television recording camera should receive about 3 per cent of the full output of the picture amplifier. In such systems picture size reduction is carried out by the optical system used for taking the exposure in order to increase thereby the illumination of the film. The quality of the so-prepared reduced scale exposures does not reach the quality of full scale exposures taken by direct exposure, and this quality is not sufficiently high for forming an accurate medical diagnosis.